In one aspect of the present invention, tissue surrounding the pulmonary vein ostia is ablated at the site in the intrapericardial space where the veins enter into the left atrium as a clinically recognized treatment for chronic atrial fibrillation. Cardiac surgeons have been entering the chest through a standard sternotomy, dissecting a tract under the superior vena cava and the inferior vena cava, and threading an ablation probe around the four pulmonary veins. The probe enters posterior to the superior vena cava, winds through the transverse sinus of the pericardium, loops around the four pulmonary veins, and exits the tract that was dissected posterior to the inferior vena cava. The tract formed posterior to the superior vena cava enters into the transverse sinus of the pericardium. The tract formed posterior to the inferior vena cava completes the path of the ablation probe around the pulmonary veins.
In order to perform the above described probe placement endoscopically, one endoscopic cannula is advanced through a thoracotomy incision, or other entry incision, into the intrapericardial space adjacent the superior vena cava, and a second endoscopic cannula is inserted into the right pleural cavity via another thoracotomy incision. This latter endoscopic cannula in the right pleural cavity is used to dissect through the right medial pleural and the pericardium posterior to the superior vena cava, guided by transillumination light emitted by the other endoscopic cannula.
This technique uses two endoscopes, and two full sets of endoscopic equipment, including endoscope, video camera, light source, video monitor and light cable. The physical space occupied by two sets of endoscopic equipment is cumbersome in the operating room, and the expense is prohibitive to hospitals. Therefore, it is desirable to perform the procedure using one set of endoscopic equipment and one endoscopic cannula.
In other types of surgical procedures, various operative techniques have been suggested for repairing regurgitant mitral valves, including surgical placement of a closed or open ring at the mitral annulus to correct a dilated annulus causing regurgitation through the valve. A “bowtie” stitch placed across the mitral orifice may reform a large orifice into two smaller openings and decrease mitral regurgitation. Alternatively, intravascular repairs include insertion of a stent or spring into the coronary sinus to reshape the mitral annulus by placing such a preformed structure into the heart's venous system.